Periodic in-track rail inspections are performed to detect critical defects before they grow enough to cause structural failure. Nondestructive inspection (NDI) technologies currently used worldwide rely mainly on conventional ultrasonic technologies. Thes e use water filled rubber wheels, containing transmitter-receiver piezoelectric transducers, that are kept in continuous contact to the rail running surface. These methods have limitations as they require contact conditions between the inspection probes an d the surface of the rail track. Although such contact ultrasonic methodologies have been extensively and successfully used in detecting many surface-breaking and internal cracks, and are proved to be reliable, they are not perfect. In fact, train derailme nts caused by broken rails, which pass inspection, still occur. Defect detectability may be affected by rail surface condition, railhead geometry, defect geometry and orientation, electrical and/or mechanical noise introduced into the transducer, and inade quate transducer-to-rail surface coupling. Moreover, inspection speeds are very low to maintain constant coupling between the two parts. In an effort to improve rail track inspections, this project proposes a non-contact ultrasonic system for periodic in-field inspections of rail tracks that has recognized advantages over conventional technologies currently available to the railroad industry. In particular, the system, consisting of a pulsed laser and an air-coupled transducer, has the following advantages : ? flexibility to discover cracks that are not detectable with methods currently available to the railroad industry; ? inspection is non-contact and remote; ? presence of oxides or oil on the rail surface enhances laser generation; ? inspection speed can be higher than with contact methods\\. The feasibility study, the development and the manufacture of a prototype will prove the capability of the proposed inspection technique for in-track rail flaw defect detection.
Call for proposal
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Funding SchemeCooperative - SMEs-Co-operative research contracts
San Joan Despi (Barcelona)
Fontenay Sous Bois
S. Maria Di Galeria Roma